Light-driven reactions that reduce CO2 have applications for solar energy storage if the reducing equivalents are derived from a renewable source. In this regard, it is desirable to replace the organic sacrificial donors typically used in molecular chromophore-catalyst schemes for CO2 reduction with protons and electrons derived from H2. We will describe the photophysics and photochemistry of molecular chromophore-catalyst systems that target driving the reverse water-gas shift reaction with light. Fluorescence quenching and transient absorption spectroscopic measurements demonstrate that the lowest singlet and triplet excited states of ZnTPP are reductively quenched by [Cp*Cr(CO)3]- in fluid solution. The resultant Cp*Cr(CO)3� radical is known to react with H2 to yield a hydride compound that, on deprotonation, regenerates the original anionic quencher. The transient [ZnTPP]- radical may be oxidized in a bimolecular reaction by Re(a,a'-diimine)(CO)3L CO2 reduction catalysts, as observed by TA spectroscopy. The rate constants for each electron transfer step will be discussed. The potential of this system to perform net photochemical oxidation of H2 to protons and electrons and reduction of CO2 to CO will be discussed.

Towards photochemical CO<sub>2</sub> reduction without sacrificial electron donors

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Towards photochemical CO2 reduction without sacrificial electron donors

Towards photochemical CO₂ reduction without sacrificial electron donors